When completing wells that are drilled vertically, horizontally or kicked off horizontally (meaning first vertical then horizontal), several formations may be encountered. These multiple formations may be completed in one run, so as to produce fluids or gases from the multiple formations up the well to maximize the production of the several formations. To complete multiple formations in a single run, a conveyance string, such as coil tubing may be used. The coil tubing, having the appropriate downhole tools attached, such as perforating tools, would be inserted downhole to the lowest formation.
Typically, a downhole tool, such as a brazer jet, operatively connected to a conveyance string, such as coil tubing, is placed adjacent the lowest formation and is used to gain access to the formation. After gaining access to the lowest formation, the brazer jet is raised uphole of the lowest formation and the formation is stimulated or fractured by pumping fracturing fluids down the annular space between the conveyance string and the wellbore.
Upon completing stimulation of the lowest formation, the coil tubing, and thus the downhole tool, is positioned to the next formation or interval of interest and the process repeated.
Similarly, other apparatus could extend though a fracturing head which are vulnerable to introduced fracturing fluids.
Fracturing fluids are typically introduced into the well from the surface through a multi-port fracturing head. The multi-port fracturing heads may have either angled side fluid ports or right angled side fluid ports.
Current multi-port fracturing heads or fracheads, have a main bore which is in fluid communication with a wellhead, the wellhead having a bore of the production tubing or conveyance string extending downhole. The frachead includes side ports which can be angled downwardly or directed at right angles to the main bore. Typically the side ports are diametrically opposed, directing the fracturing fluid at each other and colliding in the main bore.
To reduce the overall weight of the fracturing head, and the compressive load placed on a wellhead, the size of the fracturing head is usually reduced. Typically, fracturing heads with right angled side ports are shorter in height than fracturing heads with angled side ports. The shorter height reduces the overall size of the fracturing head and thus reduces the overall weight and load placed on the wellhead by the fracturing head. Further, the shortened height of the fracturing head allows the entire wellhead assembly to be significantly lower to the ground, improving accessibility, and safety for operational purposes.
However, regardless of the angle of the side ports, fracturing fluid entering the frachead is known to cause significant erosive damage to the internal surfaces of the fracturing head. The abrasive nature of proppant in the fracturing fluid coupled with the velocity and fluid dynamics of the fracturing fluid causes erosion of the internal surfaces of the fracturing head and the conveyance string, such as coil tubing. This is especially evident at high pumping rates.
In circumstances where the main bore of the frachead includes apparatus passing through the main bore, the fracturing fluid would directly impinge the apparatus. Apparatus passing or extending through the frachead include tubular and conveyance strings, such as coil tubing, wireline, E-line, slick line and the like. Herein, such apparatus will be referred to as conveyance string.
Higher pumping rates result in higher velocities of the fracturing fluid traveling inside the fracturing head, thereby increasing the erosive damage to the conveyance string. Completions with fluids which vary from low erosion gels to high erosion slick water or straight water (combined with a sand proppant and nitrogen or carbon dioxide) for the fracturing fluid create much higher erosive damage.
US Patent Application Publication No. 2003/0221838 to Dallas discloses a blast joint to protect a coil tubing string from erosion when abrasive fluids are pumped through the fracturing head. However, the blast joint taught by Dallas only protects the coil tubing from direct impingement of the fracturing fluid and does not deflect and redirect fracturing fluid into a wellbore.
It is also known to introduce fracturing fluids through fracturing heads with angled side ports, however these fracturing heads are necessarily taller, significantly larger and heavier. Using embodiments of this invention, by intercepting, deflecting and redirecting the fracturing fluid stream within a fracturing head and minimizing fluid velocities, the overall size of the fracturing head is minimized. A smaller fracturing head requires less material to manufacture, is lighter and therefore is easier, more economical and safer to operate. Using right angle side ports, the overall profile of the fracturing head is reduced. The low profile also eliminates the need costs associated therewith for a man basket, additional scaffolds and third party crane units typically required for larger fracturing heads having angled side ports.